The present invention relates to a method for determining vertical or horizontal operation of optical disk driver, especially to method for determining vertical or horizontal operation of optical disk driver by comparing the DC component of a compensation voltage of the optical disk driver with a predetermined threshold value.
FIG. 1 shows a prior art close-loop control system for an optical disk driver. As shown in this figure, the feedback signal a from the pick-up head is sent to a pre-amplifier 11 a to generate a focus error signal b. The focus error signal b is sent to a compensator 12a to generate a compensation voltage c. The compensation voltage c is sent to a motor driver 13a to driver an objective lens of the optical disk driver such that the laser light from the optical disk driver can be focused on the optical disk to be read. In other word, the objective lens has such a position to keep the optical disk in focal length of the laser light from the optical disk driver. When the optical disk driver is operated in horizontal arrangement, the compensation voltage c contains a DC bias to offset the effect due to the weight of the objective lens. When the optical disk driver is operated in vertical arrangement, the effect due to the weight of the objective lens influences the tracking of the optical disk driver and the compensation voltage c no longer contains the DC bias.
However, the close-loop control system for an optical disk driver can not detect the DC bias of the compensation voltage c. Therefore, close-loop control system is unaware of the operation arrangement (horizontal arrangement or vertical arrangement) of the optical disk driver.
It is an object of the present invention to provide a method for determining vertical or horizontal operation of optical disk driver, thus overcoming the above-mentioned drawbacks.
To achieve above object, the present invention provides a method for determining vertical or horizontal operation of optical disk driver. A feedback signal from a pick-up head of the optical disk driver is sent to a pre-amplifier to generate a focus error signal. The focus error signal is sent to a compensator to generate a compensation voltage. A low-pass filter removes high-frequency components of the compensation voltage to obtain a DC component of the compensation voltage. A comparator compares the DC component of the compensation voltage with a predetermined threshold value to discriminate the vertical or horizontal operation of optical disk driver. If the DC component of the compensation voltage is smaller than the predetermined threshold value; the vertical operation is discriminated. If the DC component of the compensation voltage is larger than the predetermined threshold value; the horizontal operation is discriminated.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: